The Web devices such as PDAs, packet PCs and mobile phones supporting HTML have however limitations in the presentation of HTML pages displayed on their screen. The limitation originally comes from the limitation of the Web device capacity, such as limitation in memory size, display attributer or limitation of the bandwidth in the mobile networks.
In order to improve presentation of the HTML pages displayed on the web device, the standardized HTML V4 proposes support for Cascading Style Sheet (CSS). The browser supporting CSS interprets link statements in of HTML V4 pages pointing to hyperlinks containing a description of the page presentation using advanced displaying capabilities such as color, line height etc. As an alternative to the link statement, the presentation stylesheet may be imbedded in the HTML page. The standard organizations such as W3C strongly push for the use of CSS in order to relieve the HTML language from the responsibilities of presentation. A description of CSS level 1 referred as REC-CSS1-19990111 is described for example in the W3C recommendation of 17 Dec. 1996; revised June January 1999.
In parallel to the evolution of HTML methodology, the Web devices themselves have increased their presentation capabilities. Unfortunately, not all of their browser support the CSS of HTML V4. The browser of some web devices do not support CSS. They only support up to HTML V3.2, as described in the HTML 3.2 Reference specification REC-html32, a W3C recommendation of 14 Jan. 1997. A web device browser supporting up to HTML 3.2 can read a HTML V4 page by skipping the link statements and the imbedded CSS. Consequently even when the web device has the hardware and software capabilities for advanced text presentation, as the browser cannot use the CSS, the presentation features of the CSS, the HTML page presentation features displayed by such web devices remain basic and not satisfying. Furthermore, the problem of the limited presentation feature may have an impact of the functionalities of web applications. For instance, functional push buttons of web pages may only be visible through advanced presentation features and thus cannot be activated is the CSS is not understood by the browser.
One example of web device having advanced presentation capabilities but operating a browser supporting web pages up to HTML V3.2 only is the Nokia 9110 mobile phone, the limitations of the browser being described in the Nokia 9110 Communicator Browser Style Guide book, a brochure published on 21 Apr. 1999.
One solution to this problem is to develop browser on these web devices which would support the CSS of HTML V4. The cost of development and distribution of dedicated browsers may prevent the device manufacturers from upgrading the browsers. One other reason preventing the web device manufacturers from handling such developments is the fact that some devices have improved presentation capabilities but not for all the features assumed to be supported by HTML V4 CSS specificities. This would imply to develop a browser very specific to the web device and which would need further upgrade with the growing device presentation capabilities.
There is thus a need to use current web devices including operating a browser supporting HTML web pages up to HTML 3.2, to be able to take advantage of their inherent advanced device presentation capabilities when displaying HTML V4 web pages including CSS.